Stepping relay accumulator



Jan. 7, 1958 R. B. JOHNSON I 1 STEPPING RELAY AQCUMULATOR Filed July 5,1952 4 Sheets-Sheet 1 INVENTOR REYNOLD B. JOHNSON ATTORNEY Jan. 7, 1958R. B. JOHNSON STEPPING RELAY ACCUMULATOR 4 Sheets-Shet 2 Filed July 5,1952 m a on mm INVENTOR REYNOLD B.JOHNSON ATTORNEY J81! 1953 R. B.JOHNSON 2,819,016

STEPPING RELAY ACCUMULATOR Filed July 5, 1952 4 Sheets-Sheet a FIG. 80

LOGIN bO- N-O BRUSH CB CBl CB2 CB5 CB6 CB R.O. EMITTER l R REYNOLDB.JOHNSON FG. 9 BY M EAVRJW ATTORNEY Ji 7; 1958 I R. B. JOHNSON STEPPINGRELAY ACCUMULATOR 4 Sheets-Sheet 4 Filed July 5, 1952 R4 R4h FIG. 8b

INVENTOR REYNOLD B JOHNSON ATTORNEY United States Patent-Q STEPPINGRELAY ACCUNIULATOR Reynold B. Johnson, Palo Alto, Calif., assignor toInternational Business Machines Corporation, New York, N. Y., acorporation of New York Application July 5, 1952, Serial No. 297,355

7 Claims. (Cl. 235-61) This invention relates in general to accumulatingdevices and in particular to a wire contact relay counter.

The principal object of the invention is to provide an inexpensivedigital type accumulator capable of operating at higher speeds thanprior art accumulators of this type.

Another object of the invention is to provide a high speed, low cost,light weight counter contained within the frame of a wire contact relayof the type disclosed in U. S. Patent No. 2,282,066 of C. D. Lake etal., issued May 5, 1942.

A further object of the invention is to provide a wire contact relaycounter having a rotary counter shaftmounted on its armature.

A still further object of the invention is to provide a wire contactrelay counter having a rotary counter shaft mounted on its armature andso designed as to enable a decimal notation to be read out according tothe binary system.

A still further object of the invention is to provide a wire contactrelay counter having an eccentrically shaped rotary counter shaft whichis adapted to facilitate the reading out of a factor entered in thecounter pursuant to the decimal system.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of examples, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a side view of the decimal readout wire contact relay countershown in a de-energized position.

Fig. 2 is a view showing the eccentrically shaped interposer shaft.

Fig. 3 is a sectional view taken along the lines 3--3 of Fig. 2.

Fig. 4 is a side view of the binary readout wire contact relay counter.

Fig. 5 is a view partly in section and partly broken away of the rotarydrum shaft.

Fig. 6 is a sectional view taken along the lines 6--6 of Fig. 5 andshowing the disposition of the code bars carried by the rotary drumshaft.

Fig. 7 is a detail view of the code bars.

Figs. 8a and 8b constitute a wiring diagram.

Fig. 9 is a timing diagram.

The relay accumulator is contained in a U-shaped frame 20 (Fig. 1) ofinsulating material. Within the frame 20 is mounted the yoke 21 to whichis fixed a magnet coil 22 and core 23. A pair of screws 24, one at thetop and one at the bottom of the frame, serve to hold the yoke inposition. A flat armature 25 is pivoted against the upper face of theyoke 21, and confined by the configuration of the frame 20 and the yoke21 in the manner as described in U. S. Patent No. 2,510,604, issued June6, 1950 to W. Pfafl et al. Two compression springs 26, only one of whichis shown, contained in sockets in the frame 20, press the armature 25against the face of sians;

4.. the yoke 21 thus causing it to rock about the bevelled edge 21a ofthe yoke as a pivot when the relay is oper ated. There is also providedthe spring 48 which pushes the insulating cap 48a against the armature25 causing the armature to be normally biased away from the core Thereis secured to the armature 25 an armature frame 33 which provides apivotable support for a rotary counter shaft assembly consisting of aratchet wheel 34 and an eccentrically shaped interposer shaft 35. Theshaft 35 is supported by and rotatably mounted between theinsulatinghubs 36 and 37 (Fig. 2) which are rotatably supported by theframe 33.

The interposer shaft 35 which is a formed wire comprises ten individualeccentric segments which may be divided into five groups of two each.The two segments forming a group are offset from each other by whileadjacent groups are offset by 36 from each other. This shaft, as shallbe pointed out subsequently, is advanced ina counterclockwise direction(Fig. l) in 36 steps so that one group of the eccentric segments willalways be in a vertical position (Fig. 2). The upper segment (Fig. 2)when in a vertical position will engage the corresponding wire contact30 while the lower segment will slightly clear the insulating bar 38.Thus it is to be noted that this disposition of oppositely disposedsegments of a particular group tends to prevent deflection of the shaftunder the load of the wire contact 30. The segments of the interposershaft as shown in Figs. 2 and 3 have been numbered to correspond to thevalue to be read out when the segment is in contact with itscorresponding wire contact 30.

The left-hand (Fig. 2) outside bend of the wire shaft 35 is contained inthe slot 39 of the hub 36 and confined in position by the common contactring 40. The righthand outside bend of the wire shaft 35 is contained inthe slot 41 of the hub 37 wherein it is fastened. The slot 39 in the hub36 imparts the torque required to drive the wire shaft 35 while the slot41 in the hub 37 imparts the torque required to rotate the hub 37 in thebearing fastened to the frame 33.

A ten toothed ratchet wheel 34 is secured to the hub 36 as shown in Fig.2 which is adapted to cooperate with a pair of pawls 43 and 44.

The pawls 43 and 44 are rotatably mounted on separate studs 45 and 46both of which are secured to the frame 20. The respective toothedportions 43a and 44a of the pawls 43 and 44 engage the ratchet Wheel 34under the influence of the spring 47. When the armature 25 is attractedby the energization of the magnet coil 22, the engagement of the pawl 43with a tooth of the ratchet 34 will cause the ratchet 34 and interposershaft 35 to rotate in a counterclockwise (Fig. 1) direction forapproximately 18 or & of a revolution. As the ratchet 34 is rotated in acounterclockwise direction, the pawl 44 will ride over a ratchet toothand engage in the succeeding tooth. As the armature 25 is restored toits normal or tie-energized position by the joint action of the spring26 and the compression spring 48, the ratchet 34 and shaft 35 continueto rotate in a counterclockwise direction being driven by the pawl 44while the pawl 43 rides over a tooth to engage the ratchet inpreparation for the suc seeding magnet energization. When the armatureis returned to its normal position, the action of the pawl 44 causes theratchet 34- to rotate another 18 or of a revolution. Thus, the totaltravel of the ratchet is A of a revolution for each electrical impulsereceived by the coil 22; that is, revolution in attracting the armatureplus & revolution in releasing the armature. Obviously, each time theratchet is moved A of a revolution, the shaft 35 will be correspondinglyrotated.

two units, the raised portions 58 and 60 of the 2 code bar will engagethe corresponding common (c) and 2 wire contacts 30; when the ratchet 34is moved three units, the single raised portion 61 of the 3 code bar 52will jointly engage the corresponding common, 1 and 2 wire contacts 30;when the ratchet 34 is moved four units, the raised portions 62 and 63of the 4 code bar 52 will jointly engage the corresponding common and 4wire contacts 30 (such as shown in Fig. 5) to complete a circuittherebetween; when the ratchet 34 is moved five units, the raisedportions 64 and 65 of the 5 code bar 52 will engage the common and 1wire contact 30 and the 4 Wire contact 30; when the ratchet 34 has beenmoved six units, the raised portions 66 and 67 of the 6 code bar 52 willrespectively engage the common wire contact 30 and the 2 and 4 wirecontacts 52; when the ratchet 34 has been moved seven units, the raisedportion 68 of the 7 code bar 52 will jointly engage the common, 1, 2 and4 wire contacts 30; when the ratchet 34 is moved eight units, the raisedportions 69 and 70 of the 8 code bar 52 will respectively engage thecommon and 8 wire contacts 30; and when the ratchet 34 is moved nineunits, the raised portions 71 and 72 of the 9 code bar 52 willrespectively engage the common, 1 and 8 wire contacts 30.

In the disposition of the code bars 52 about the periphery of the drum51, the 4 code bar 52 is positioned directly opposite the 9 code bar 52and being so disposed is the only code bar having a raised portion, suchas 62, which is adapted to jointly engage the carry wire contacts 49 andthe common wire contacts 50. For example, when the ratchet wheel 34 isstanding in its 9 position, and with a subsequent energization of thecoil 22 causing the armature 25 to be attracted thereto, the carry wirecontacts 49 and the common wire contacts 50 will be engaged by theraised portion 62 of the 4 code bar 52 to complete a circuit for settingup a carry operation as shall be explained subsequently.

Circuit diagram The functioning of the decimal readout relay of Fig. 1shall be described in reference to an assumed problem. Let it be assumedthat the value 196 in the card 74 (Fig. 8a) is to be entered and readout of the relays 73U, 713T and 73H, each of which is similar inconstruction to the relay of Fig. 1.

The record card 74 containing the value 196 is placed in a sensingposition between the conductive roll 75 and a set of brush sensingelements 76 of which there is one for each card column being sensed. Asusual, the presence of a digit representing perforation in any cardcolumn will allow the related brush 76 to make electrical contact withthe conductive roll 75. The particular mechanism for feeding recordcards and sensing the perforated data therein form no part of thepresent invention.

and, accordingly, have been shown in a diagrammatic manner in Fig. 8a.It might be added at this time that in the circuit diagram are shown anumber of cam operated contacts, all of which are designated with theprefix CB. The cams for controlling these contacts are all mounted on acommon shaft which is caused to rotate continuously and insynchronization with the feeding of the record card through a suitablepower source in a well known manner. The timing of the contactscontrolled by these cams is shown in Fig. 9 for one machine cycle, andit will be understood that this is repeated.

Each brush 76 is connected to a respective one of the group of relaysidentified as R1, R2 and R3 which become energized upon the detection ofa perforation by the corresponding brush 76. With the energization ofthe respective relays R1, R2 and R3 at 6, 9 and 1 index time, a holdcircuit will be established for these relays by the cam controlledcontacts CB1 through the respective a contacts. The circuit establishedfor energizing the relay R2, for example, is traceable as follows: line77 coupled to a positive source of potential (not shown), cam controlledcontacts CB making eachindex point time as There is embedded in theframe 20 the contactors 27 and 28 with the contactor 28 coupled to theterminal wires (not shown) of the coil 22. Extending through thecontactor 27 is a wire contact spring 30 which is adapted to contact thecommon contact ring 40 when the armature 25' is in its normal ortie-energized position such as shown in Fig. 2. The upper end of thiswire is hooked as shown in Fig. 1 with the hook extending through a hole31 in a plate 32. The plate 32 is positioned on the top of the frame 20and held thereto by the upper screws 24. The plate 32 is adapted to bemoved to left or right to decrease or increase the pressure against theupper end of the wire 30. As indicated in Fig. 2, there is providedadditional spaced aligned wire contacts 30 which are adapted to besuccessively engaged by the corresponding numbered segment of the shaft35 as the shaft 35 is rotated through the stepping of the ratchet 35caused by the movement of the armature 25. It is to be noted from Fig. 2that each of the segments of the shaft 35 representative of the digits 0to 8, inclusive, have a single pair of corresponding wire contacts 30associated therewith while the 9 segment of the shaft 35 has associatedtherewith two pairs of wire contacts 30, the purpose of which will bemade clearer subsequently in the description of the wiring diagram.

There is also provided two additional pairs of wire contacts 49 and 50which become effective during a carry operation. For example, when thecoil 22 is energized with the 9 segment engaging its corresponding wirecontact pair 36, the armature 25 upon being attracted to the coil willcause the left-hand end 35a of the conductive shaft 35 to contact thewire contacts 49 and the common contact ring 40 to engage the wirecontacts 50. This operation will enable a carry circuit to be set up ina manner which shall be described subsequently in more detail. There isprovided a contactor 27 for each pair of the wire contacts 39, 49 and50.

It is believed pertinent to mention at this time with reference to Fig.2 showing the 9 Wire contact 30 engaging the corresponding contact, thatthe electrical circuit established is from the 9 contactor 27, the 9wire contact 30, the 9 segment of the conductive shaft 35, the commoncontact ring 40, the corresponding wire contacts 30 and contactor 27.

A modification of the decimal readout electromagnetic relay of Fig. 1 isshown in Fig. 4 wherein the interposer shaft 35 of Fig. 2 has beenreplaced by a fluted insulating drum 51 having nine code bars 52. Thedevice of Fig. 4 enables digital values to be read out according to abinary code.

The drum 51 is mounted on the shaft 53 which is rotatably supported atthe pivots 54 and 55 (Fig. 5) by the frame 33. The nine code bars 52 aredisposed about the periphery of the drum at intervals of 36 in a mannersuch as shown in Fig. 6. It is to be noted from Fig. 7 that no code baris provided for Zero. The code bars 52 are retained and electricallyconnected by the rings 56 and 57 positioned at extreme ends of the drum51.

In the binary readout relay only five wire contacts 30 are providedwhere one of the wire contacts 30 (labeled C in Fig. 5) will engage thecommon raised portion of each bar, such as 58 of the 2 bar 52, while theother wire contacts 30 respectively representative of the digits 1, 2, 4and 8 will be engaged either singly or in combination by the appropriatecode bars. As in the case of the decimal readout relay, there are alsoprovided wire contacts 49 and 50 which will be engaged by theappropriate code bars when the armature is attracted to the coil duringthe time when a carry operation is called for.

Fig. 7 shows the raised portions required in each of the code bars 52 totranspose the decimal system into a binary system. For example, when theratchet 34 is moved one unit, the raised portion 59 of the 1 code bar 52will be in position to jointly engage the corresponding common (c) and 1wire contacts 30; when the ratchet 34 is moved 5 shown in Fig. 9,contacts R41 and R27d normally closed, conductive roll 75, 9 perforationin record 74,'corre-' sponding brush 76, pickup coil of relay R2, andthen to conductor 82 coupled to the negative terminal of the source ofpotential.

The energization of the relay R2 will close the contacts R2b at "9 timethereby enabling nine separate pulses to be applied to the relay 73T bythe cam controlled contacts CB2 (see Fig. 9 for timing). As previouslymentioned, each pulse applied to the relay 73T will cause its ratchet 34to step such that at index time the 9 segment of the interposer shaft 35will be in engagement with the corresponding pair of wire contacts 30.Thus as a result the pair of 9 contacts 9a and 9b (Fig. 8b) of the tensorder will be closed. It may be pointed out that in the circuit diagramvarious relays are shown at points remote from the contacts which theycontrol. This has been done to simplify the wiring connections, and toclearly identify related parts the relays have been shown in dottedoutline adjacent the contacts they control.

-In a similar manner the relays R1 and R3 will be energized respectivelyat 1 and 6 index time causing the corresponding b contacts to close,thereby enabling the relays 73H and 73U to be pulsed l and 6 times,respectively. This operation will close the 6 contacts 30 in the unitsorder and the 1 contacts in the hundreds order.

At 0 index time with the contacts 9b in the tens order now closed, acircuit will be established with the making of the contacts CBS and CB7at this time (see timing diagram of Fig. 9) to condition the tens orderfor a carry-over operation through the energization of relay R6. Thiscircuit may be traced as follows: conductor 77 (Fig. 8b) coupled to thepositive terminal of a source of potential (not shown), contacts CB nowclosed, line 78, total relay contacts R4e (Fig. 8b) as shown, conductor79, contacts 9b of the tens order now closed, conductor 80, pickup coilof relay R6, conductor 81, total relay contacts R4g normally closed,contacts CB7 now closed, and then to line 82 coupled to the negativeterminal of the source of potential. The circuit just traced will resultin the relay R6 being energized and the associated contacts R6a (Fig.8b) and R6b (Fig. 8a) being closed. An obvious hold circuit for relay R6will be set up by the cam controlled contacts CB4 through the contactsR611. It is pointed out that whenever a 9 is sensed in the units orhundreds order, the corresponding relays R5 and R7 will be similarlyenergized.

Whenever the associated ratchet wheel of the 'units, tens, or hundredsorder passes from 9 to 0, the associated carry contacts 50 will beclosed thus enabling a circuit to be established for energizing thecorresponding carry relay R8, R9 or R10 when the cam controlled contactsCB2 make. As an example, the circuit established for energizing theunits carry relay R8 is traced as follows: conductor 77, cam controlledcontacts CB2 now closed, contacts R4h normally closed, conductor 87,units carry contacts 50 now closed, conductor 88, pickup coil of relayR8 and then to the negative conductor 82. .An obvious hold circuit forrelay R8 will be set up through the contacts R811 by the cam controlledcontacts CB4.

Now proceeding along the assumption that the units carry relay R8 isenergized, when the cam controlled contacts CB3 make as shown in thetiming diagram of Fig. 9, a carry operation will take place causing therelay 73T to be pulsed and advanced one unit.

Thus when the contacts CB3 close and with carry relay contacts R8b (Fig.8a) now shifted, a circuit will be established for pulsing the nexthigher order relay. This circuit may be traced from line 77, contactsCB3 now closed, contacts R8b now closed, R22b normally closed, relay 731and then to conductor 82. Since relay 73T has standing therein a 9 valuecausing relay R6 to be energized as previously described, a parallelcircuit from the shifted contacts R8b will be set up for pulsing therelay 'R73H, thereby extending the carry to the next higher order. Thiscircuit is traceable from the shifted contacts R8b as follows: contactsRob now closed, R9b as shown, R23b normally closed, relay 731-1 and thento conductor 82. Thus under the assumed carry conditions, the relay 73Twill be stepped one unit to 0 while the relay 73H will be stepped to the2 position.

After the amounts in a particular group of cards have been successivelyaccumulated in the associated accumulating devices through the pulsingof the corresponding relays 73U, 73T and 731-1, a total printingoperation is initiated by the operator closing the total print switch89. With the switch 89 now closed, the total relay R4 will be energizedthrough an obvious circuit when the cam controlled contacts CB9 close asshown in Fig. 9. A hold circuit is established for relay R4 through thecontacts R4a by the cam controlled contacts CB8. The energization ofrelay R4 will enable the value standing in the various orders to be readout during the succeeding cycle. It is pointed out that during thissucceeding cycle the contacts R4 will be opened to prevent any furtherentries being made into the accumulators. While it is not any part ofthis invention, it is obvious that the feeding of cards during a totalprint cycle may be halted in a well known manner.

A description of the manner of reading out the units order, for example,will now be set forth. It is recalled that the 6 contacts in the unitsorder is closed. Thus when the cam controlled contacts CB6 close at 6index time and with the brush 83 contacting the 6 segment of the emitter84, a circuit will be established for reading out the value 6. Thiscircuit is traced as follows: line 77 (Fig. 8b), contacts CB6 and Recnow closed, 6 segment of the emitter 84, 6 contacts 30 of units ordernow closed, conductor 85, contacts R4f now shifted, magnet 86, and thento conductor 82. As is well known, the energization of magnet 86 willcontrol the usual recording devices, such as punching or printing, in awell known manner. It is to be realized that concurrently with thereading out of the units order the remaining orders are likewise beingread out.

After the printing or punching of the total, as the case may be, hasbeen taken, the restoring of the counters to 0 position will be broughtabout by the closing of the restoring key 90 which will cause therestoring relays R21, R22, R23 and R27 to pick up when the camcontrolled contacts CB11 close as shown in the timing diagram of Fig. 9.A holding circuit for relays R21, R22 and R23 will be set up through itsassociated 11 contacts and the corresponding zero relay contacts R2411,R25b and R26b. A holding circuit for relay R27 will be set up throughthe now closed contacts R27a and any one of the contacts R21c, R220 andR230. The energization of relay R27 will close contacts R2712 (Fig. 8a)to prevent the taking of a total and R27a' (Fig. 8a) to prevent theentering of data during a restoration operation.

The energization of the relays R21, R22 and R23 will transfer theassociated contacts R211), R221) and R23b (Fig. 8a) thereby enabling aseries of CB2 impulses to be applied to the magnet coils 73U, 73T and731-1. The series of CB2 impulses will advance the respective countersto zero. When a counter reaches the zero position, the 0 contact 30(Fig. 8b) will close picking up the corresponding zero relays R24, R25,and R26, as the case may be, through a circuit established when the camcontrolled contacts CB6 make. As an example, the circuit established forenergizing the zero relay R24 of the units order is traceable asfollows: conductor '77, contacts CB6 now closed, R27c now closed, 0contacts 30 now closed, conductor 91, relay R24 and then to the negativeconductor 82. As each of the zero relays R24, R25 and R26 be comeenergized, the associated contacts R24b, R25b and R26! open to break thehold circuits of the correspond- 7 ing restoring relays R21, R22 and R23thereby enabling the respective counters to remain at the now assumedzero position.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

1. In a device of the class described, a coil, an armature, a yoke forsaid coil, a supporting frame pivotably supporting said armature, aplurality of wire contacts arranged in parallel alignment and having oneend secured by said frame, each of said contacts representative of adifferent digit, a rotary counter shaft having conductive elementsrespectively representative of the digits 1, 2, 3, 4, 5, 6, 7, 8 and 9,ratchet means secured to said shaft, said ratchet means and said shaftbeing rotatably carried by said armature, the alignment of said contactsbeing in parallel with the longitudinal axis of said shaft, pawl meansfor stepping said ratchet, said pawl means being secured to said frame,said pawl means causing said ratchet to be stepped each time saidarmature is attracted to said coil and restored to its normal position,said conductive elements successively contacting said Wire contacts assaid ratchet is stepped.

2. A device such as claimed in claim 1 wherein said rotary counter shaftcomprises a formed wire having ten individual eccentric segments, saidsegments being ivided in five groups of two each, said segments Within agroup being offset from each other by 180 while adjacent ones of saidsegments are offset 36 from each other.

3. A device such as claimed in claim 2 wherein said rotary counter shaftcomprises drum means having circumferentially disposed a plurality ofcode bars, said code bars effecting selection of certain of the wirecontacts pursuant to the binary system during the stepping of saidratchet.

4. In a device of the class described, a coil, an armature pivotablysupported with respect to said coil, a counter shaft, ratchet meanssecured to said shaft, said shaft being rotatably supported by saidarmature, said shaft comprising a formed wire having a plurality ofindividual numerically valued conductive eccentric segments, a pluralityof contacts each having one free end arranged to engage thecorresponding one of said conductive segments as said ratchet steps saidshaft, pawl means, said pawl means causing said ratchet to be moved oneunit when said armature is attracted to said coil and restored to itsnormal position.

5. In a device of the class described, a coil, an armature pivotablysupported with respect to said coil, a

counter shaft, ratchet means secured to said shaft, said shaft beingrotatably supported by said armature, said shaft comprising drum meanshaving circumferentially disposed a plurality of code bars, a pluralityof contacts respectively representative of the digits 1, 2, 4 and 8,means for successively feeding a number of pulses representative of adecimal value to said coil, pawl means, said pawl means causing saidratchet to step said drum means one unit for each of Said pulses, saidcode bars being so arranged to engage said contacts either singly or incombination for converting said decimal value to the binary system.

6. In a device of the class described, drum means having a plurality ofelongated bars circumferentially disposed and respectivelyrepresentative of the digits 1, 2, 3, 4, 5, 6, 7, 8 and 9, a pluralityof contacts respectively representative of the digits 1, 2, 4, 8, carrycontact means, said bars each having projections adapted to contact saidcontacts either singly or in combination as said drum means is rotatedin a step-like manner, said bar representative of the 4 digit having anadditional projection for engaging said carry contact means as said drummeans is stepped from a 9 position to a 0 position, and means forstepping said drum through nine positions respectively designated as 1,2, 3, 4, 5, 6, 7, 8 and 9.

7. In a device of the class described, relay means including anarmature, shaft means having ten rotative positions, said shaft meanshaving a number of eccentric conductive segments equal to saidpositions, a common contact ring engaging one end of said shaft, saidshaft means rotatably supported by said armature, means upon energizingsaid relay means for causing said shaft to be stepped through saidpositions, a plurality of contact means, there being at least one ofsaid contact means corresponding to each of said segments, an additionalcontact means for engaging said ring as said shaft is stepped from thefirst to the last of said positions, each of said contact means engagingthe corresponding one of said segments as said shaft is stepped throughsaid positions, and additional contact means for respectively engagingsaid ring and said shaft during the interval as said shaft is steppedfrom the last to the first of said positions.

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